Last month's column on "microaggressions" was my most debated yet. Thanks for reading and commenting.

So this month, let's explore how the microaggression dynamic works in all societies, and why some people live in denial of it. Brace yourself for a bit of theory . . .

All societies, when defining themselves, decide who is "us" and who is "them." So do countries. In the name of sovereignty, nation-states must decide who is a member (a citizen) and who is not (a foreigner). (If they didn't, there'd be no point to citizenship.)